Mineral oil containing 1, 2-dialkoxy benzene as an oxidation inhibitor



Patented Jan. 5, 1954 MINERAL OIL CONT BENZENE ASfANO AINING-LZ-DIA-LKOXY-I XIDATION INHIBITOR William C. Hollibaugh, Springfield,Pa., assignor to Sun Oil. Company,

poration ofNcw-Jersey Philadelphia, .Pa.,. a. cor- No Drawing.Application June-23,1950; Serial No. 170,021-

6 Claims.

Thisxinvention relates to mineral oil inhibited Many oxidationinhibitors have been proposedfor lubricating oil. Among the best suchinhibitors that have been proposed are certain alkylated phenols,particularly tertiary-butyl-substituted phenols, such as 2,6-ditertiarybutyl-4- methylphenol. Such alkylated phenols are generally eifective toinhibit oxidative deterioration of lubricating oil under ordinaryconditions of use.

Certain types of lubricating oil, however,- are used under unusuallysevere temperature: conditions, e. g. 250-450 F.; and oxidationinhibitors which are suitable at ordinary temperature conditions of use,e. g. 100-250 F., are frequently much less efiective and thereforeunsuitable when used in such lubricating oil under such severetemperature conditions.

Lubricating oil suitable for use under severe temperature conditions isrequired to have certain general specifications. For example, it musthave relatively high flash point (A. S. T. M. D9246), e. g. 350 F. orabove, and preferably above the highest temperature to which the oil isto be subjected; otherwise the oil will be too volatile for effectiveuse under severe temperature conditions.

Lubricating oil for certain specific applications involving severetemperature conditions must have additional specifications. For example,lubricating oil for use in automotive fluid couplings, wheretemperatures of about 400 F. must be withstood, are generally requiredto have an S. U. viscosity at 100 F. within the approximate range170-190, and an S. U. viscosity at 210 F. not substantially less than45. The present invention relates to the inhibition against oxidation ofsuch lubricating oil and other lubricating oil suitable for use undersevere temperature conditions.

I have discovered that 1,2-dialkoxy benzenes oxidation inhibitor. dationinhibitor for wherein the. alkoxy groupseach contain1-9' carbon. atomsare effective oxidation inhibitorsv for lubricatingv oil. used undersevere temperature conditions. The. term 1,2-dialkoxy benzene, isintended to indicatea substituted benzene having twoalkoxy substituentson adjacent carbon atoms of I the ring, butno hydroxy substituents.Preferred 1,2.-dialkoxy benzenes for use according to the inventionv arethose wherein the alkoxy groups contain 24Sv carbon atoms.

Oxidation inhibitors for use according to they invention should besubstantially non-volatile at the. temperature atwhich the oil is used,i. e., they should have normal boiling points higher than thetemperature of use of the oil. Generally 1,,2-dialkoxy benzenes havehigh enough normaliboilingpointsfor almost all severe temperature usesordinarily. encountered.

Catechol diethyl ether (1,2-diethoxy benzene) is particularlyadvantageous for use according to the. invention; for it, hasbeen foundthat although catechol diethyl ether is generally inferior to at leastone, widely used alkylated phenol of v the prior art as an oxioil underordinary temperature conditions of. use, catechol diethyl ether is onthe other hand distinctly superior to that same alkylated phenoloxidation inhibitor as an inhibitor for oil under severe temperatureconditions of use.

The amount of 1,2-dialkoxy benzene used in a given amount of lubricatingoil will vary according to the degree of oxidation inhibition desired.Generally, satisfactory results are obtained with 0.01-2.00 weightpercent of 1,2-dialkoxy benzene.

The following example illustrates the invention:

The oil tested in this example was a solventrefined, dewaxed,acid-treated, and clay-treated distillate from mixed-base crudepetroleum, the distillate having an S. U. viscosity at 10 F. of about185 seconds, a viscosity index of about 90, and a flash point above 350F. Two samples of such oil were tested for oxidation stability undersevere temperature conditions by subjecting each to a temperature of 400F. in an oven for hours, air being passed through the sample during thisperiod at the rate of two bubbles per second. Before and after theoxidation period, the amount of naphtha-insoluble material in eachsample and the S. U. viscosity at 210 F. of each sample were determined.

Sample No. 1 contained one weight percent of 2,6-ditertiarybutyllemethyl phenol as oxidation inhibitor, and sample'No. 2 containedone weight Percent In- Percent Increase in crease in Sample No. Naphtha-S. U. Vis- Insoluble cosity at Materials 210 F.

The above results show that lubricating oil inhibited with2,6-ditertiary buty1-4-methyl phenol undergoes greater oxidativedeterioration under severe temperature conditions than does the same oilinhibited with catechol diethyl ether.

On the other hand, lubricating oil inhibited with 2,6-ditertiarybutyl-i-methyl phenol generally undergoes less oxidative deteriorationunder ordinary temperature conditions of use than does the same oilinhibited with catechol diethyl ether. For example, an oil havingproperties generally like those of the oil tested in the example above,but having S. U. viscosity at 100 F. of about 160, was found to be morestable in the turbine oil oxidation stability test (A.S.T.M. D943-4'7T)which is conducted at 203 F., when inhibited with 2,6-ditertiarybutyl-4-methyl phe- 1101 than when inhibited with catechol diethylether. I

Thus, it is seen that the efiectiveness of lubrieating oil oxidationinhibitors depends on the conditions to which the oil is subjectedduring use, and that catechol diethyl ether gives superior results inoil used under severe temperature conditions, as compared with a priorart oxidation inhibitor, such as 2,6-ditertiary butyllmethyl phenol.

Although in the preceding example, 1,2-diethoxy benzene is used as anexample of a 1,2- dialkoxy benzene, similar results may be obtained whenother 1,2-dialkoxy benzenes are used wherein the alkoxy groups contain1-9- carbon atoms, e. g. 1,2-dimethoxy benzene, 1,2-dibutoxy benzene,1,2-diamoxy benzene, etc. It is generally preferred that the two alkoxygroups contain the same number of carbon atoms; this is not strictlynecessary, however, and generally satisfactory results may be obtainedwhen using 1,2-dialkoxy benzenes such as l-ethoxy-Z-methoxy benzene,l-propoxy-2-methoxy benzene, l-butoxy-4-butyl-2-methoxy benzene,i-hexyloxy-2-methoxy benzene, etc.

I claim:

1. A composition comprising: a major proportion of mineral lubricatingoil suitable for use under severe temperature conditions; and a minorproportion constituting an oxidationinhibiting quantity of a1,2-dialkoxy benzene wherein the alkoxy groups contain 1-9 carbon atoms.

2. Composition according to claim 1 wherein said oil has a flash pointof at least about 350 F.

3. Composition according to claim 1 wherein the weight percent of said1,2-dialkoxy benzene in the composition is about 0.01-2.00%.

4. Composition according to claim 1 wherein said 1,2-dialkoxy benzene is1,2-diethoxy benzene.

5. The method of lubricating metal parts which comprises: contactingsuch parts with mineral lubricating oil at a temperature within therange from 250 F. to 450 F., said oil containing a minor proportionconstituting an oxidation inhibiting quantity of a 1,2-dialkoxy benzenewherein the alkoxy groups contain 1-9 carbon atoms.

6. A composition consisting essentially of a major proportion of minerallubricating oil suitable for use under severe temperature conditions;and a minor proportion constituting an oxidation-inhibiting quantity ofa 1,2-dialkoxy benzene wherein the alkoxy groups contain 1-9 carbonatoms.

WILLIAM C. HOLLIBAUGI-L References Cited in the file of this patentvUNITED STATES PATENTS Number Name Date Re. 23,239 ,Rosenwald June 6,1950 2,067,960 Werntz Jan. 19, 1937 2,362,516 Wasson Nov. 14, 194

1. A COMPOSITION COMPRISING: A MAJOR PROPORTION OF MINERAL LUBRICATINGOIL SUITABLE FOR USE UNDER SEVERE TEMPERATURE CONDITIONS: AND A MINORPROPORTION CONSTITUTING AN OXIDATIONINHIBITING QUANTITY OF A1,2-DIALKOXY BENZENE WHEREIN THE ALKOXY GROUPS CONTAIN 1-9 CARBON ATOMS.